Swab assembly



Jan. 13, 1970 J. A. WILSON SWAB ASSEMBLY 2 Sheets-Sheet 1 Filed March 14, 1968 FIGURE 2 FIGURE 3 JAMES A. WILSON FIGURE I N VENTOR.

Jan. 13, 1970 J. A. WILSON 3,489,066

SWAB AS SEMBLY Filed March 14, 1968 2 Sheets-Sheet 2 59u 41m 560 I l F/GURE 4 JAMES A. WILSON INVENTOR.

United States Patent 3,489,066 SWAB ASSEMBLY James A. Wilson, 4225 San Gabriel Drive, Dallas, Tex. 75229 Filed Mar. 14, 1968, Ser. No. 713,147 Int. Cl. F0111 1/10; E21b 41/00; F16j 9/12 US. Cl. 92-180 21 Claims ABSTRACT OF THE DISCLOSURE A swab assembly for swabbing a flow conductor, such as pipe, tubing or casing and the like, having a mandrel and a multiple section swab mounted on the mandrel movable on the mandrel between a lower position thereon in which the swab closes the flow conductor during upward movement of the assembly through the flow conductor and an upper position wherein the swab assembly permits movement of fluids therethrough during downward movement of the swab assembly through the flow conductor, the multiple sections of the swab being detachably connectable to one another.

This invention relates to well tools and more particularly to well swab assemblies and multiple element swabs therefor.

An object of the invention is to provide a new and improved well swab assembly which is longitudinally movable in a flow conductor for lifting fluids therein.

Another object is to provide a well swab assembly having a multiple section swab, each of whose elements includes a tubular support on which is mounted a resilient seal element for sealing between the tubular support and the flow conductor, and means for detachably connecting two or more of the swab elements to form the swab.

Still another object is to provide a swab assembly wherein one or more of the swab elements are mounted on a mandrel for movement between a lower closed position wherein the central longitudinal passage of the swab is closed during the upward movement of the swab assembly through the flow conductor and the seal elements of the swab sections are expanded into sealing engagement with the flow conductor by the fluid load supported thereby during upward movement of the well swab assembly in the flow conductor.

Still another object is to provide a new and improved swab having a plurality of sections, each having a rigid tubular member and a resilient annular seal element secured thereto, the lowermost seal element having a bottom seal edge or surface for engaging a seal surface of a mandrel on which the swab is mountable.

Still another objectis to provide a swab wherein the means for connecting adjacent ends of adjacent swab sections permits some pivotal movement of the sections relative to one another to facilitate movement of the swab through crooked or curved portions of a flow conductor.

Additional objects and advantages will be readily apparent from the reading of the following description of a device constructed in accordance with the invention, and reference to the accompanying drawings thereof, where- FIGURE 1 is a vertical partly sectional view showing a well swab embodying the invention with the swab thereof in its uppermost position as the well swab assembly is moved downwardly in a flow conductor;

FIGURE 2 is a vertical enlarged sectional view of the upper swab section of the multiple section swab illustrated in FIGURE 1;

FIGURE 3 is an enlarged vertical sectional view of the bottom swab section;

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FIGURE 4 is a vertical sectional view of a swab section which is connectable between the top and bottom sections;

FIGURE 5 is a sectional view taken on line 55 of FIGURE 1; and

FIGURE 6 is a vertical sectional view of modified form of an upper swab section usable in place of the swab section illustrated in FIGURE 2.

Referring now to the drawings, the well swab assembly embodying the invention includes a mandrel 10 having a rod provided with a plurality of radially outwardly extending longitudinal ribs 13 intermediate its ends, a connector head 14 threaded on the upper end of the rod and a seat and guide body 15 threaded on the lower end of the rod. The connector head has opposed slots 16 and downwardly facing stop shoulder 17 which extends radially outwardly in opposite directions from the rod. The connector head has an upper reduced threaded end portion 18 by means of which the mandrel may be secured to a suitable connector or sub 19 of the usual assembly of flexible line tools by means of which the well swab assembly is moved through a flow conductor seat by a flexible member, such as a wire line. The seat and guide body 15 has a top annular downwardly and outwardly extending seat surface 20 and a plurality of longitudinally extending slots 21 which facilitate the flow of well fluids past the seat and guide body during longitudinal movement of the swab assembly in a flow conductor.

A swab 25 is mounted on the rod for longitudinal movement relative thereto between the connector head and the seat and guide body. The swab includes a lower element or section 26 and an upper element or section 27 which are detachably secured to one another by means which permit some articulation or pivotal movement of one element relative to the other. The bottom swab section 26 includes a rigid tubular support 28 on which is bonded, moulded or otherwise secured a tubular resilient seal element 29. Downward movement of the swab 25 on the mandrel is limited by the engagement of the bottom annular edge 31 of the tubular element 28 with the seat surface 20 of the seat and guide body 15 which also provides a metal to metal seal to close the lower end of the tubular support 28.

The seal element 29 has a lower downwardly and inwardly extending annular or bevel surface 32, an upwardly and outwardly extending annular surface 33 which increases in external diameter upwardly so that the top end of the surface is somewhat greater in diameter than the bottom portion thereof. For example, if the swab section 26 is to be used in a 2-inch ID well conductor, the external diameter B of the lower edge of the surface 33 of the seal element 29 may be 1.940 inches and the external diameter A of its top edge may be 1.955 inches where the length C of the annular surface 33 is 1 inches so that the outer surface 33 inclines downwardly and inwardly from the vertical at approximately A of a degree.

The seal element has an upwardly and inwardly convergent outer surface 35 to facilitate movement of the upper portion of the seal element past downwardly facing internal obstructions of the flow conductor. The seal element also has an annular upwardly opening top recess 36 defined by a downwardly and inwardly inclined annular surface 37 which extends from the top edge of the surface 35 and an upwardly and inwardly extending surface 38 which extends to the outer surface of the tubular support 28. The surface 36 may incline downwardly at an angle of approximately 30 degrees from the horizontal and the surface 38 may incline at an angle of 15 degrees from the vertical.

The upper or top swab element 27 similarly includes a rigid tubular support 41 whose annular lower end portion 42 is flared outwardly at a slight angle, for example, degrees, to provide an annular downwardly facing shoulder 43 which is engageable with the top annular end surface or shoulder 44 of the tubular support 28. A substantially tubular resilient seal element 45 is bonded or moulded about the tubular support 41 and has an annular surface 46 which decreases in external diameter downwardly so that it has a slight downward and inward angle of approximately ,4 of a degree. For example, if the top swab element is to be used in a 2-inch ID diameter flow conductor, the diameter A of the top edge of its external surface 46 may be 1.955 inches and its diameter B at its lower edge may be 1.939 inches where the length C of the seal element is 1%, inches. The bottom external surface 48 of the resilient seal element slopes downwardly and inwardly, for example, at an angle of 30 degrees from the horizontal, and its bottom internal surface 49 slopes upwardly and inwardly from the bottom edge of the surface 48 at an angle of approximately 30 degrees from the vertical. An internal annular portion or lip 50 of the resilient body extends substantially the width of the flared portion 42 so that when the top portion of the tubular support 28 of the bottom section 26 is telescoped up wardly into the flared portion 42 of the tubular support 41 of the top swab section, the lip portion of the tubular support 41 is compressed to effect a seal between the two swab sections.

The seal element 45 also has an upper annular upwardly and inwardly extending surface 55, and a top recess 56 defined by the upwardly divergently. extending annular surfaces 57 and 58 which may have the same angles of inclination as the similar surfaces 37 and 38 of the seal element 29. The external diameters of the seal elements 29 and 45 at the upper edges of their external surfaces 33 and 46 are preferably equal to or slightly less than the internal diameter of the flow conductor in which the swab assembly is to be used in order that the swab may be moved relatively easily down.- wardly in the flow conductor. The provision of the recesses 36 and 56 in the upper ends of the elements 29 and 45, respectively, and the upwardly and outwardly inclination of the annular surfaces 37 and 57 defining the outer sides of the recesses facilitates an upward and inward deformation of the upper outer edge portions of the seal elements relative to their tubular rigid supports 28 and 41, respectively, if the outer surfaces of the seal elements engage the internal surfaces of the flow conductor during the downward movement of the swab assembly in a flow conductor. Conversely, when the swab assembly is moved upwardly in a flow conductor, the force of any liquid above the swab assembly on the upper surfaces of the seal elements tends to move the upper outer portions of the seal elements defined by their recesses downwardly and outwardly and into engagement with the internal surfaces of the well flow conductor.

In use, the swab assembly is movable longitudinally in a well flow conductor by means of a flexible line which is secured to the connector head 14 by means of the sub 19 of the usual set of wire line tools. The weight of the swab assembly as well as of the set of wire line tools by means of which the mandrel head is connected to the wire line, causes the swab assembly to move downwardly through the flow conductor by gravity and overcomes any friction between the seal elements and the internal surfaces of the flow conductor tending to resist such downward movement of the swab assembly through the flow conductor, the mandrel is in its lowermost position relative to the swab 25 due to the resistance offered to the downward movement of the swab by any fluids present in the flow conductor and also due to any frictional engagement of the seal elements with the internal surfaces of the flow conductor, wherein further downward movement of the mandrel relative to the swab is limited by the engagement of the shoulder 17 of the connector head 14 with the annular top end shoulder 59 of the tubular support 41 of the top swab section 27. The fluids present in the flow conductor may therefore flow through the longitudinal passage provided by the tubular supports 28 and 41 and the passages between the ribs 13 of the rod as the well swab assembly is moved downwardly in the flow conductor.

The diametrical distances across the diametrically opposed outer longitudinal surfaces of the ribs 13 are slightly less than the internal diameters of the rigid tubular supports 28 and 41 so that some lateral movement of the two swab sections may take place relative to the mandrel. During such downward movement of the swab assembly through a crooked or curved portion of the flow conductor, the somewhat yieldable connection of the upper portion of the rigid tubular support 28 and the lower flared portion 42 of the rigid tubular support 41 of the swab section permits some lateral or pivotal movement of one swab section relative to the other to facilitate movement o(f the assembly through such curved or crooked portion of the flow conductor. Should the two sections actually separate due to extreme lateral forces being exerted on the two swab elements the downwardly and outwardly flared lower portion 42 facilitates the reconnection of the two sections to one another.

After the swab assembly has moved downwardly to a desired position in the flow conductor, an upward pull is imparted to the wire line by means of which the assembly swab has been lowered through the flow conductor, and the mandrel 11 is moved upwardly relative to the swab until the annular seat surface or edge of the bottom tubular support 28 is engaged by the beveled seat surface 20 of the seat and guide body 15 whereupon the longitudinal passage provided by the tubular supports 28 and 41 is closed at its lower end. During such initial upward movement of the mandrel the swab 25 is held against the upward movement both by gravity, by the frictional engagement of its seal elements 29 and 45 with the internal surfaces of the flow conductor, and the force exerted on the seal elements by the the column of fluids located thereabove. Once the seat surface 20 has engaged the seat surface 31 of the tubular support 28, further upward movement imparted to the mandrel also results in upward movement of the swab and any liquids trapped above the swab are now moved upwardly in the well flow conductor by the swab assembly. The downwardly acting forces exerted on the upwardly facing surfaces of the seal elements 29 and 45 by such slug or column of liquids, tend to compress downwardly the upper portions of the seal elements and, due to the provision of the recesses 36 and 56 in their top ends, the upper portions of the seal elements move radially outwardly and into sealing engagement with the internal surfaces of the flow conductor. The greater the downward forces exerted On the upper portions of the seal elements of the swab assembly, the greater the longitudinal length of the upper portions of the seal elements thereof which are compressed longitudinally and expanded radially outwardly into engagement with the internal surfaces of the flow conductor. If the external diameters of the seal elements are slightly smaller than the internal diameter of the flow conductor, upward movement of the swab assembly, when liquid is present in the flow conductor, the swab, creates a pressure differential across the seal elements which expands the upper portions of the seal elements into engagement with the internal surfaces of the flow conductor.

The compression of the lip portion 50 of the seal element 45 of the upper swab section between the flared portion 42 of the support 41 of the upper swab section and the upper portion of the tubular support 28 provides a fluid tight seal therebetween. At the same time, some lateral or pivotal movement of the upper tubular support 41 relative to the tubular support 28 of the two sections is permitted to facilitate movement of the swab assembly through crooked or curved portions of the flow conductor.

Under certain conditions, as for example, if the liquid load in any particular flow conductor to be raised by the swab assembly is relatively light, the flow conductor has portions of the extreme crookedness or curvature, or it is likely that due to the presence of sand and debris in the liquid in the flow conductor which may cause the swab assembly to become lodged in the flow conductor, the well swab assembly may be used with only the bottom swab section 26 on the mandrel. It will, of course, be apparent that a swab assembly having only the lower swab section on the mandrel may pass more easily through crooked or curved sections of a flow conductor than one having two swab sections and that a smaller upward force need be exerted on the swab assembly when it is required to dislodge a single seal element, than two seal elements, when it becomes necessary to remove the swab assembly after it is lodged by sand and the like against movement in the flow conductor.

In other well installations where greater liquid loads are to be raised, and the condition of the flow conductor permits an intermediate swab section 27a may be interposed between the lower swab section 26 and an upper swab section 27. The intermediate swab section 2711 illustrated in FIGURE 4 may be similar in structure to the upper swab element 27 and, accordingly, its elements have been provided with the same reference numerals, to which the subscript a has been added, and the corresponding elements of the upper swab section 27. The intermediate swab section 27a differs from the upper section 27 only in that its tubular support 41 has an upper end portion which extends upwardly of the top of its resilient element 45a so that it may be telescoped in the flared lower end portion 42 of the upper element 45 of the upper swab section 27. The top end portion of the tubular support 28 of the lower swab section is then telescoped in the flared portion 42a of the tubular support 41a of the intermediate swab section.

It is apparent, of course, that if desired more than one such tubular section intermediate section 27a may be interposed between the lower and upper swab sections 26 and 27 as desired, and that the length of the rod 12 of mandrel 11 may be increased to accommodate the greater length of a swab comprised of such greater number of swab sections.

In FIGURE 6 is illustrated a modified form of the upper swab section for use with the lower swab section 26. The swab section 27b illustrated in FIGURE 6 being similar to the swab section 27 illustrated in FIGURE 2, its elements have been provided with the same reference numerals, to which the subscript b has been added, as the corresponding elements of the swab section 27. The swab section 27b differs from the swab section 27 in that its tubular rigid support 41b is not provided with a flared lower end portion, such as the portion 42 so that the bottom stop surface 43b is provided by the lower end of the tubular support. The internal annular lower end surface 49b of the resilient element 45b slopes upwardly and inwardly from the lower end of the external upwardly and outwardly sloping surface 48b to the lower end of a substantially vertically annular surface 52 which extends to the annular bottom end surface 43b of the tubular support. The vertical annular internal surface 52 is of somewhat greater diameter than the internal diameter of the tubular support but preferably slightly less than its external diameter so that when the lower end of the upper section 27b is telescoped over the upper end portion of the tubular support 28 of the lower swab section, the lower end portion of the resilient element 45b is compressed radially outwardly, to effect a fluid tight seal between the lower portion of the resilient element and the upper end portion of the rigid tubular support 28.

It will be apparent that where the upper swab section 27b is used with the lower swab section 26, the downward telescopical movement of the upper section on the tubular support of the lower section is limited by the engagement of the top annular surface 44 of the tubular support 28 with the bottom annular surface 43b of the tubular support 41b and that due to the resilience of the element 45b some pivotal movement between the two sections may take place. The use of the upper swab section 27b instead of the section 27 may be preferred in some applications, as for example, where the swab is used in a relatively large flow conductor, for example, a well casing.

It will now be seen that a new and improved swab assembly has been illustrated and described which has a mandrel 11 on which a well swab 25, having one or more sections, is movably mounted, and that if the well swab includes two or more swab sections the adjacent ends of the adjacent swab sections are detachably connected to one another.

It will further be seen that the seal elements of the swab sections are longitudinally compressed and radially expanded into sealing engagement with 'the flow conductor when the swab assembly is moving a slug or column of liquids upwardly in the flow conductor so that each swab section bears a portion of the total load of such slug.

It is preferable that each seal element be of greater length than internal recesses of the flow conductor, such as coupling recesses at the locations of connections of two tubing sections by a collar or coupling, in which the swab assembly is to be used so that each swab element may span such internal recesses as it moves therepast and minimize the loss of the load being moved thereby during the passage of the swab section by such recess.

It will further be seen that a new and improved multiple section swab has been illustrated and described which includes a pair of sections, each having a rigid tubular support and a seal element for sealing between the tubular support and the internal surfaces of a flow conductor during upward movement of the swab through the flow conductor, and that the rigid tubular supports of the two swab sections are detachably connected together by means which permit some lateral and pivotal movement of one section relative to the other to facilitate passage of the swab through crooked or curved sections of a flow conductor.

The foregoing description of the invention is explanatory only and changes in the details of the construction illustrated may be made by those skilled in the art, within the scope of the appended claims, without departing from the spirit of the invention.

What is claimed and desired to be secured by Letters Patent is:

1 A swab assembly including: an elongate mandrel having an upwardly facing annular seat surface adjacent ts lower end and downwardly facing stop means adjacent its upper end; and a swab disposed on said mandrel for movement thereon between seat surface and said stop rneans, said swab including: a pair of sections each havmg a rigid tubular support and a resilient seal element disposed about and secured to said tubular support, the tubular support of the lower section having a top end portion extending upwardly of its seal element and the tubular support of the upper swab element having an enlarged bottom end portion, the top end portion of the tubular support of the lower swab section being telescopical in said enlarged lower end portion for detachably connecting the two swab sections to one another.

2. The swab assembly of claim 1, wherein the seal element of said upper swab section has an annular lip portion disposed in said bottom end portion and compressible between said top and bottom end portions of said tubular supports to seal therebetween.

3. The swab assembly of claim 2, wherein said tubular support of said upper swab section has means providing a downwardly facing stop means for limiting downward movement of said tubular support of said upper swab section on said top end portion of said tubular support of said lower swab section.

4. The swab assembly of claim 3, wherein said bottom end portion of said tubular support of said upper swab section is annular in form and flares outwardly and downwardly.

5. The swab assembly of claim 4, wherein said seal elements decrease in diameter downwardly and are provided with annular top recesses whose outer sides are defined by upwardly and outwardly inclined annular surfaces.

6. The swab assembly of claim 5, wherein said seal elements are spaced longitudinally from one another when said swab sections are connected to one another.

7. The swab assembly of claim 6, wherein said tubular supports have larger internal passages than the maximum lateral width of said mandrel to permit limited lateral movement of said swab sections relative thereto.

8. The swab assembly of claim 1, wherein said seal elements decrease in diameter downwardly and are provided with annular top recesses whose outer sides are defined by upwardly and outwardly inclined annular surfaces.

9. The swab assembly of claim 8, wherein said seal elements are spaced longitudinally from one another when said swab sections are connected to one another.

10. The swab assembly of claim 9, wherein said tubular supports have larger internal passages than the maximum lateral width of said mandrel to permit limited lateral movement of said swab sections relative thereto.

11. A swab mountable on a mandrel having an upwardly facing seat surface and stop means spaced above said seat surface, said swab including: a pair of sections each having a rigid tubular support and a resilient seal element disposed about and secured to said tubular support, the tubular support of the lower section having a top end portion extending upwardly of its seal element and the tubular support of the upper swab element having an enlarged bottom end portion, the top end portion of the tubular support of the lower swab section being telescopical in said enlarged lower end portion for detachably connecting the two swab sections to one another.

12. The swab of claim 11, wherein the seal element of said upper swab section has an annular lip portion disposed in said bottom end portion and compressible between said top and bottom end portions of said tubular supports to seal therebetween.

13. The swab of claim 12, wherein said tubular support of said upper swab section has means providing a downwardly facing stop means for limiting downward movement of said tubular support of said upper swab section on said top end portion of said tubular support of said lower swab section.

14. The swa b of claim 13, wherein said bottom end portion of said tubular support of said upper swab section is annular in form and flares outwardly and downwardly.

15. The swab of claim 14, wherein said seal elements decrease in diameter downwardly and are provided with annular top recesses whose outer sides are defined by upwardly and outwardly inclined annular surfaces.

16. The swab of claim 15, wherein said seal elements are spaced longitudinally from one another when said swab sections are connected to one another.

17. The swab of claim 16, wherein said tubular supports have larger internal passages than the maximum lateral width of said mandrel to permit limited lateral movement of said swab sections relative thereto.

18. The swab of claim 17, wherein said seal elements decrease in diameter downwardly and are provided with annular top recesses whose outer sides are defined by upwardly and outwardly inclined annular surfaces.

19. A swab mountable on a mandrel having an upwardly facing seat surface and stop means spaced above said seat surface, said swab including: a pair of sections each having a rigid tubular support and a resilient seal element disposed about and secured to said tubular support, the tubular support of the lower section having a top end portion extending upwardly of its seal element and the upper swab section having an internally enlarged lower end portion, the top end portion of the lower swab section being telescopical in said enlarged lower end portion for detachably connecting the two sections to one another.

20. The swab of claim 19, wherein the seal element of said upper swa b section provides said internally enlarged lower end portion, said internally enlarged lower end portion being of smaller internal diameter than the exterior diameter of said top end portion for causing said lower end portion to be expanded resiliently outwardly by said top end portion.

21. The swab of claim 20, wherein said tubular support of said upper swab section has means providing a downwardly facing stop means engageable by the top end portion of the tubular support of said lower section for limiting downward movement of said upper section relative to said lower section.

References Cited UNITED STATES PATENTS CARROLL B. DORITY, JR., Primary Examiner US. Cl. X.R. 

